1. Field of the Invention
The invention relates to a traffic signal device and method and more particularly to a traffic signal device that can be erected at an intersection in anticipation of a loss of power or to supersede a permanent traffic signal in the event of a failure, and a method of using such a traffic signal device.
2. Description of the Related Art
Portable or backup traffic signal devices are known. See, for example, U.S. Pat. Nos. 2,401,940, 2,603,700, 2,941,185, 3,046,521, 3,867,718, 4,401,969, 5,208,584, 5,252,969, 5,400,019, 5,659,305, 5,900,826, 5,986,576, 6,118,388, 6,392,563, 6,496,123 and U.S. Design Pat. No. D457,827.
Certain of these devices portable or backup traffic signal devices can be remote controlled, such as is disclosed in U.S. Pat. No. 3,867,718 to Moe, U.S. Pat. No. 5,986,576 to Armstrong, and U.S. Pat. No. 6,118,388 to Morrison. Additionally, U.S. Pat. No. 6,392,563 discloses a traffic light backup system using light-emitting diodes and including a rechargeable battery associated with an auxiliary light, which is engaged in the event of a power failure.
Further, traffic lights including solar panels are disclosed in U.S. Pat. No. 6,268,805 to Simon and U.S. Pat. No. 6,522,263 to Jones.
U.S. Pat. No. 4,401,969 to Green et al., col. 1, lines 20-27, discloses that it is now known to provide traffic control systems consisting of a master control unit, and one or more slave units controlled by the master unit, in which the communication between the units in order to obtain a desired sequence of light signals is by means of radio wave transmissions from the master unit, and as examples may be mentioned those disclosed in U.S. Pat. Nos. 2,829,362 and 3,168,685. In Green, a portable traffic control system is disclosed in which receivers are controlled from a central transmitter and a carrier signal employed is modulated by two different modulation signals in order to command a green light to be shown. Further, in Green, the receipt of a carrier signal with only a single pilot modulation causes production of a red signal.
U.S. Pat. No. 5,805,081 to Fikacek discloses portable traffic signals including a control module. In one aspect of Fikacek, a remotely controlled power hoist is attached to the top of the control module for raising and lowering the traffic signal. Fikacek additionally discloses that, in place of manual controls, a transmitter can be mounted in the a module and used with receivers mounted in other traffic signals for synchronizing the traffic signal with the other traffic signals. Fikacek, which incorporates the disclosure of Green by reference, discloses modulated carrier signals are transmitted via an antenna to slave traffic signals, where they are processed to activate and de-activate the lights of the slaves.
U.S. Pat. No. 5,252,969 to Kishi discloses a temporary traffic signal system wherein a pair of signal stands are installed at spaced locations adjacent a traffic restricted area. Kishi discloses that the stands have an operation starting arrangement for initiating operation of the controllers of both of the stands at the same time, or a signal transmission arrangement for transmitting the operating condition data between the stands, so that the lights of both stands are operated in a controlled and synchronized relationship with each other. Col. 1 of Kishi, lines 36-40, disclose that it is an object of one aspect of that invention to provide a temporary signal system capable of operating both the parent and child signal stands by the transmission of setting and synchronizing data from the parent signal stand to the child signal stand to thereby conform actual time in a timer of the parent signal stand to that of the child signal stand for synchronizing the flashing operations between the parent and child signal stands.
However, what is needed is a traffic signal device and system that ensures the operability of the traffic signal devices in an intersection, and/or synchronicity of the timer or clock of each of the traffic signals, through bi-directional communication between the devices in the intersection. It would additionally be desirable for such traffic signal devices to be inexpensive, modular, portable and/or self-contained.